`3/7-2/5`

`=1/35>0`

`=>3/7>2/5`

`b,9>8`

`=>1/9<1/8`

`=>5/9<5/8`

`d,8/7>1`

`7/8<1`

`=>8/7>7/8`

a) Ta có: \(\dfrac{3}{7}=\dfrac{15}{35}\)

\(\dfrac{2}{5}=\dfrac{14}{35}\)

Do đó: \(\dfrac{3}{7}>\dfrac{2}{5}\)

b) Ta có: 9>8

nên \(\dfrac{5}{9}< \dfrac{5}{8}\)

c) Ta có: \(\dfrac{8}{7}>1\)

\(1>\dfrac{7}{8}\)

Do đó: \(\dfrac{8}{7}>\dfrac{7}{8}\)

a: \(\dfrac{-7}{6}=\dfrac{-7\cdot3}{6\cdot3}=\dfrac{-21}{18}\)

\(\dfrac{-11}{9}=\dfrac{-11\cdot2}{9\cdot2}=\dfrac{-22}{18}\)

mà -21>-22

nên \(-\dfrac{7}{6}>-\dfrac{11}{9}\)

b: \(\dfrac{5}{-7}=\dfrac{-5}{7}=\dfrac{-5\cdot5}{7\cdot5}=\dfrac{-25}{35}\)

\(\dfrac{-4}{5}=\dfrac{-4\cdot7}{5\cdot7}=\dfrac{-28}{35}\)

mà -25>-28

nên \(\dfrac{5}{-7}>\dfrac{-4}{5}\)

c: \(\dfrac{-8}{7}< -1\)

\(-1< -\dfrac{2}{5}\)

Do đó: \(-\dfrac{8}{7}< -\dfrac{2}{5}\)

d: \(-\dfrac{2}{5}< 0\)

\(0< \dfrac{1}{3}\)

Do đó: \(-\dfrac{2}{5}< \dfrac{1}{3}\)

a)      31/24

b)   5/6

c)     29/9 

bài 1

mik luoi lam

\(\dfrac{13}{17}< \dfrac{30}{34}\)                                        \(\dfrac{9}{8}>\dfrac{5}{7}\) 

 \(\dfrac{15}{7}< \dfrac{8}{3}\)                                        \(\dfrac{5}{7}< \dfrac{7}{5}\)                     

\(\dfrac{16}{20}=\dfrac{4}{5}\)

a) \(\dfrac{5}{9}< \dfrac{7}{9}\)

b) \(\dfrac{7}{6}>\dfrac{6}{6}\)

c) \(\dfrac{3}{14}< \dfrac{5}{14}\)

d) \(\dfrac{5}{8}< \dfrac{9}{8}\)

Bài 2: 

a: 5/4<7/4

b: 2/3=34/51

9/17=27/51

mà 34>27

nên 2/3>9/17

Bài 3: 

a: 1/3+3/8=8/24+9/24=17/24

b: 7/6+5/18=21/18+5/18=26/18=13/9

Từng bài 1 thôi nhé

Bài 2: 

a: 5/4<7/4

b: 2/3=34/51

9/17=27/51

mà 34>27

nên 2/3>9/17

Bài 3: 

a: 1/3+3/8=8/24+9/24=17/24

a)\(\frac{3}{4}<\frac{4}{5}<\frac{5}{6}\)

b) \(\frac{3}{4}<\frac{5}{7}<\frac{7}{28}\)
 

C)\(\frac{5}{6}<\frac{7}{8}\)

d) \(\frac{7}{8}>\frac{5}{7}\)  
 

Tik chj nha

a)3/4<4/5<5/6

b)7/28<5/7<3/4

c)5/6<7/8

d)5/7<7/8

cái này lớp 5 học rùi mà nếu mẫu số ps nào lớn hơn thì ps đó lớn hơn = thì so tử số tick nha giải tiếp

\(5\frac{1}{2}>5\frac{1}{4}\)

\(12\frac{7}{12}< 12\frac{5}{8}\)

\(6\frac{5}{7}< 12\frac{5}{8}\)

\(9\frac{6}{7}>8\frac{7}{8}\)

#Yuki

a) Ta có:

\(\dfrac{8}{9}=\dfrac{40}{45}\)

\(\dfrac{7}{5}=\dfrac{63}{45}\)

\(\Rightarrow\dfrac{8}{9}< \dfrac{6}{5}\left(\dfrac{40}{45}< \dfrac{63}{45}\right)\)

b) Ta có:

\(\dfrac{3}{4}=\dfrac{15}{20}\)

\(\dfrac{4}{5}=\dfrac{16}{20}\)

\(\Rightarrow\dfrac{3}{4}< \dfrac{4}{5}\left(\dfrac{15}{20}< \dfrac{16}{20}\right)\)

Câu `5`

`a)` Ta có:

`8/9 < 1 ; 7/5>1`

Vì: `8/9 < 1 < 7/5` nên `8/9 < 7/5`

`b)3/4= 15/20`

`4/5 = 16/20`

Vì: `15/20 < 16/20` nên `3/4<4/5`